Basic At Command Syntax; S-Parameters - Symbol MC909X Integrator Manual

2 - 42 MC909X Integrator Guide

Basic AT Command Syntax

A command line is made up of three elements:
Prefix - consists of the characters "AT" or "at" or, to repeat the execution of the previous command line,
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"A/" or "a/".
Body - made up of individual commands described later. Space characters (IA5 2/0) are ignored and
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may be used for formatting purposes, unless they are embedded in numeric or string constants. The
termination character may not appear in the body. The modem can accept at least 40 characters in the
body.
Termination character - may be selected by a user option (parameter S3). The default is CR.
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The format of Basic Syntax commands, except for the D and S commands, is as follows:
<command>[<number>]
where:
<command> is either a single character, or the "&" character followed by a single character per V.250; or
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the "%" character followed by a single character, the "*" character followed by a single character, or the
"^" character followed by a single character.
<number> is a string of one or more characters from "0" through "9" representing a decimal integer value.
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Commands expecting a <number> are noted in the description of the command. If <number> is missing
from such a command (<command> is immediately followed by another <command> or the termination
character), the value "0" is assumed. If a command does not expect a <number> and a number is
present, an error occurs. All leading "0"s in <number> are ignored by the modem.
Additional commands may follow a command (and associated parameter, if any) on the same command line
with a separation character. The actions of some commands cause the rest of the command line to be ignored.

S-Parameters

Commands that begin with the letter "S" are known as "S-parameters". The number following the "S" indicates
the "parameter number" referenced. If the number is not recognized as a valid parameter number, an ERROR
result code issues. Immediately following this number, either a "?" or "=" character must appear. "?" is used to
read the current value of the indicated S-parameter; "=" sets the S-parameter to a new value.
S<parameter_number>?
S<parameter_number>=[<value>]
If the "=" is used, the new value to be stored in the S-parameter is specified in decimal following the "=". If no
value is given (i.e., the end of the command line occurs or the next command follows immediately), the
S-parameter specified may be set to 0, or an ERROR result code issues and the stored value remains. The
ranges of acceptable values are given in the description of each S-parameter.
If the "?" is used, the modem transmits a single line of information text to the DTE. The text portion of this
information text consists of exactly three characters, giving the value of the S-parameter in decimal, with
leading zeroes included.